Basic Qualification · B-007 Radio wave propagation · B-007-006-009
Quand la propagation sur la bande de 80 mètres est-elle généralement la MOINS efficace?
- AL'hiver pendant le jour
- BL'été pendant le jour
- CPendant les soirs d'hiver
- DPendant les soirs d'été
Correct answer: B — L'été pendant le jour. Question tirée de la banque officielle d'ISDE.
Why
During the day, the Sun's ultraviolet light creates a dense layer in the upper atmosphere that absorbs lower frequency signals like those on the 80-metre band. The full explanation — and one for every question — is in Pro.
Practise this section
Radio wave propagation is section B-007 of the Basic exam: How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.
Drill B-007 — free, no account